153. 寻找旋转排序数组中的最小值

class Solution { public:     int findMin(vector& nums) {         if(nums.size()==1)             return nums[0];         int n = nums.size()-1;         int left = -1,right = n;         int res = nums[0];         if(nums[0] < nums[n])             return res;         while(left+1             int mid = left+(right-left)/2;             if(nums[mid] < nums.back())                 right = mid;             else                 left = mid;         }         return nums[right];     } }; 

98. 验证二叉搜索树

通过中序遍历，得到有序的数组，在判断数组是否严格递增

/**  * Definition for a binary tree node.  * struct TreeNode {  *     int val;  *     TreeNode *left;  *     TreeNode *right;  *     TreeNode() : val(0), left(nullptr), right(nullptr) {}  *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}  *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}  * };  */ class Solution { public:     void traversal(TreeNode* root,vector& res) {         if(root==NULL)             return;         if(root->left)             traversal(root->left,res);         res.push_back(root->val);         if(root->right)             traversal(root->right,res);     }     bool isValidBST(TreeNode* root) {         if(!root)             return true;         vector res;         traversal(root,res);         for(int i=1;i             if(res[i] <= res[i-1])                 return false;         }         return true;     } }; 

118. 杨辉三角

res即dp数组，寻找res[i][j]的更新规律

class Solution { public:     vector> generate(int numRows) {         vector> res(numRows);         for(int i=0;i             res[i].resize(i+1);             res[i][0] = res[i][i] = 1;             for(int j=1;j                 res[i][j] = res[i-1][j]+res[i-1][j-1];             }         }         return res;     } };